An escaped snake is thought to have strangled two young brothers found dead at an apartment in Canada. Rough cut (no reporter narration)

PHOTOS have emerged which show the two boys killed by a python playing in an anaconda tank as autopsy confirms they died of asphyxiation.

The boys' mother Mandy Trecartin has hundreds of photos of Connor and Noah Barthe on her Facebook page, including a few showing the brothers happily scrubbing the glass enclosure, which she identified as an anaconda habitat.

It was not clear whether the enclosure is the one that held the python.

Another photo shows the boys playing in sand in another snake tank.

A preliminary autopsy shows the boys died of asphyxiation as it was revealed that a snake found in the same room may have thought they were prey after they had spent the day around farm animals.

Connor and Noah Barthe seen here with an unidentified friend cleaning one of Jean-Claude Savoie's reptile tanks. Picture: Facebook

Connor and Noah Barthe's great-uncle, David Rose, said they spent their last day with the snake's owner, Jean-Claude Savoie, and his son - enjoying a barbecue and swimming at the family farm.

"They enjoyed life to a maximum, their last day was spent playing with friends,' Rose said, adding that the two families stocked up on groceries before heading to Mr Savoie's farm.

"There they played with llamas, and goats and horses, they played with dogs and cats in the hay loft," he said. "They went for a ride with Jean-Claude on his tractor and he even let them steer. They had a super day."

Paul Goulet, founder and co-owner of Little Ray's Reptile Zoo in Ottawa, said snakes don't recognise humans as a source of food, but if the children smelled like animals, it could explain an attack.

Connor and Noah Barthe play with the sand in one of the tanks. Picture: Facebook

"If a snake sees an animal moving, giving off heat and smells like a goat, what is it? It's a goat,'' Mr Goulet said.

The shocked Canadian town of Campbelltown planned a vigil today for the Barthe boys.

The snake apparently escaped from its enclosure, slithered through a ventilation system and fell through the ceiling into the room where the young boys were sleeping, authorities said on Tuesday.

Snake expert John Kendrick, a manager at the Reptile Store in Hamilton, Ontario, said it sounds like the snake might have been spooked.

Connor and Noah Barthe. Picture: Facebook

Pythons can sense heat, and if they are startled they can grab something, Mr Kendrick said. He said their muscles run lengthwise through their body, so they are not very stable unless they are holding on to something.

It's possible that the python was just holding on to what it landed on, Mr Kendrick said.

"Once they are in constricting mode, any part of their body that is touching something that moves, they'll wrap it,'' he said. "I've seen snakes with two different prey items at the same time, one with the back of the body and one with the front. It could have been an incident like that.''

Police are treating the deaths in Campbellton, New Brunswick, as a criminal investigation.

A python escaped a pet shop and strangled two boys to death in their sleep. Picture: Marc Mccormack

The brothers had been visiting Mr Savoie's apartment. He owned an exotic pet store on the floor below, Royal Canadian Mounted Police Sgt. Alain Tremblay said. Sgt. Tremblay said the 4.3-metre snake was being kept inside the apartment, not inside the pet store as authorities had previously stated.

Steve Benteau, a spokesman for the provincial Natural Resources Department, said no permit was issued for an African rock python, and provincial authorities weren't aware it was being kept at the apartment. The department said the snake is generally only permitted in accredited zoos, unless there is a special permit.

Sgt. Tremblay said the snake was housed in a large glass enclosure that reached the ceiling of the apartment and escaped through a small hole in the ceiling connected to the ventilation system. He said the snake made its way through the ventilation system, the pipe collapsed and the snake fell.

The friend of the boys was sleeping in another room and was unharmed.

A memorial sits outside the Reptile Ocean exotic pet store in Campbellton, New Brunswick, Canada. Autopsies will be performed on two young boys who were strangled in their sleep by a large 4.3 meter African rock python.

Mr Savoie, told the Global News television station that he didn't hear a sound and discovered the "horrific scene'' when he went into his living room on Monday morning.

Police said the snake was killed by a veterinarian.

Reptile expert Bry Loyst, curator of the Indian River Reptile Zoo in Ontario, said police have been seeking his advice. He said police told him it wasn't the first time that the python had escaped its enclosure. Police were not available to confirm that late on Tuesday.

Connor Barthe, 7, and Noah Barthe, 5, were killed by a snake which had escaped its enclosure. Picture: Facebook/Mandy Trecartin

The Reptile Ocean store where the snake escaped. The dead boys were sleeping in the apartment above the shop. Picture: Google Earth

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